1. Field of the Invention:
This invention relates to the control of Douglas-fir beetle (Coleoptera:Scolytidae) infestation in felled trees. More particularly the invention concerns a method for regulating the aggregation of the bark beetle Coleoptera:Scolytidae which exploits controlled release formulation of 3-methyl-2-cyclohexen-1-one (MCH).
2. Description of the Prior Art:
The Douglas-fir bark beetle infests Douglas-fir forests throughout much of the Northwestern United States. Its population occasionally reaches epidemic proportions, especially in trees weakened by windthrow or disease. It was discovered in 1971 (Kinyer, G. W., Fentimon, A. F. Jr., Folty, R. L., Rudinsky, J. A., J. Econ. Ent., (1971), 64, 970.) that the frass of the female Douglas-fir beetle contains a pheromone, 3-methyl-2-cyclohexen-1-one (MCH), which was later shown (Rudinsky, J. A., Furniss, M. M., Kline, L. N., Schmitz, R. F., Can. Entomol., (1972), 104, 815., Furniss, M. M., Kline, L. N., Schmitz, R. F., Rudinsky, J. A., Ann. Entomol. Soc. Amer., (1972), 65, 1227), to have antiaggregative effects on adult beetles. In 1974 it was shown (Furniss, M. M., Daterman, G. E., Kline, L. N., McGregor, M. D., Trostle, G. C., Pettinger, L. F., and Kudinsky, J. A., Can. Entomol., (1974), 106, 381.) that, when released optimally, (i.e. 1 g/acre/day) the pheromone served to reduce beetle attacks upon felled host trees by 96 percent. The pheromone was dispensed in that experiment as neat material from small metal canisters mounted at even spacings around the tree on wooden stakes. This trial served to demonstrate the effectiveness of the treatment, and refined the optimum rate of pheromone release to a narrow range (0.6-1.3 g/acre/day).